Nanoparticulate mineralized collagen glycosaminoglycan materials directly and indirectly inhibit osteoclastogenesis and osteoclast activation

Abstract

The ability of the extracellular matrix (ECM) to direct cell fate has generated the potential for developing a materials‐only strategy for tissue regeneration. Previously, we described a nanoparticulate mineralized collagen glycosaminoglycan (MC‐GAG) material that efficiently induced osteogenic differentiation of human mesenchymal stem cells (hMSCs) and calvarial bone healing without exogenous growth factors or progenitor cell expansion. In this work, we evaluated the interactions between MC‐GAG and primary human osteoclasts (hOCs). In the absence of hMSCs, mineralized Col‐GAG materials directly inhibited hOC viability, proliferation, and resorption in contrast to nonmineralized Col‐GAG, which demonstrated a modest inhibition of resorptive activity only. Cocultures containing differentiating hMSCs with hOCs demonstrated increased hOC‐mediated resorption only on Col‐GAG while MC‐GAG cocultures continued to inhibit resorption. Unlike Col‐GAG, hMSCs on MC‐GAG expressed increased amounts of osteoprotegerin (OPG) protein, the major endogenous osteoclast inhibitor. Interestingly, OPG expression was found to be antagonized by small mothers against decapentaplegic1/5 (Smad1/5) phosphorylation, an obligate pathway for osteogenic differentiation of hMSCs on MC‐GAG, and potentiated by extracellular signal‐regulated kinase (ERK1/2) phosphorylation. Collectively, these results suggested that the MC‐GAG material both directly inhibited the osteoclast viability, proliferation, and resorptive activity as well as induced hMSCs to secrete osteoprotegerin, an antiosteoclastogenic factor, via a signalling pathway distinct from osteogenic differentiation.

Anisotropic mineralized collagen scaffolds accelerate osteogenic response in a glycosaminoglycan-dependent fashion

“…We have previously shown that mineralized collagen scaffolds containing isotropic pores and CS6 induce MSCs to produce OPG when seeded with MSCs to enhance bone regeneration. 44,45 Suggesting the anisotropic mineralized scaffold may be particularly interesting for future studies to explore MSC-osteoclast interactions.…”

“…Mineralized collagen scaffolds were fabricated using previously described procedures. 10,11,21,27,[40][41][42][43][44][45] In a cooled, jacketed vessel, 1.9 w/v% type I bovine collagen (Sigma-Aldrich, Missouri, USA), 0.84 w/v% chondroitin-6-sulfate (Sigma-Aldrich), and Ca(OH) 2 , H 3 PO 4 , and Ca(NO 3 ) 2 $4H 2 O were thoroughly homogenized, making sure to prevent collagen clumping. The mineralized collagen suspension was transferred to 7.62 Â 7.62 cm aluminum molds to create isotropic scaffolds.…”

Anisotropic mineralized collagen scaffolds accelerate osteogenic response in a glycosaminoglycan-dependent fashion

“…Interestingly, the expression of the osteoclast inhibitory factor OPG 60 was upregulated in all scaffold groups, particularly in the anisotropic mineralized scaffold. We have previously shown that mineralized collagen scaffolds containing isotropic pores and CS6 induce MSCs to produce OPG when seeded with MSCs to enhance bone regeneration 44,45 .…”

“…Mineralized collagen scaffolds were fabricated using previously described procedures 10,11,21,27,[40][41][42][43][44][45] . In a cooled, jacketed vessel, 1.9 w/v% type I bovine collagen (Sigma-Aldrich, Missouri, USA), 0.84 w/v% chondroitin-6-sulfate (Sigma-Aldrich), and Ca(OH)2, H3PO4, and Ca(NO3)2·4H2O were thoroughly homogenized, making sure to prevent collagen clumping.…”

Stiffness of Nanoparticulate Mineralized Collagen Scaffolds Triggers Osteogenesis via Mechanotransduction and Canonical Wnt Signaling

“…Within the realm of calvarial regeneration, we have previously described the ability of an ECM-inspired nanoparticulate mineralized collagen glycosaminoglycan (MC-GAG) material to induce osteogenic differentiation of primary, bone marrowderived hMSCs in the absence of exogenous growth factors via autogenously activating the canonical bone morphogenetic protein receptor (BMPR) signaling pathway via phosphorylation of small mothers against decapentaplegic-1/5 (Smad1/5) (12)(13)(14)(15)(16)(17)(18). More importantly, MC-GAG also induced calvarial regeneration as a progenitor cell-free, exogenous growth factor-free material in rabbits in a manner that approached 60% of the stiffness and strength of the outer cortex of native calvarium (15).…”